The present invention relates to surface cleaning apparatus and more particularly to apparatus for applying a powdered cleaning composition.
Heretofore, a wide variety of methods and apparatus have been developed for cleaning surfaces such as carpeted surfaces. These methods have included the application of a liquid cleaning solution which may be agitated or worked into the surface and which is subsequently removed by vacuuming. Such wet cleaning methods possess certain drawbacks with respect to particular types of carpets. For example, the cleaning solution may damage the carpet fibers or cause shrinkage of the carpet material if improperly applied. The apparatus used to practice such methods has generally been bulky and cumbersome in use. Such apparatus may include a source of vacuum, a solution supply tank, a solution collection tank and a hand-held implement. The hand-held implement may or may not include an agitator brush but typically includes one or more spraying nozzles and a suction nozzle to remove the cleaning solution from the carpet fiber.
In order to overcome some of the inherent drawbacks of a wet carpet cleaning method, methods and apparatus have been developed for cleaning carpeted surfaces through the application of a moist coherent cleaning powder. The powder must be applied evenly over the surface and is typically agitated or worked into the surface and then removed by the application of a vacuum. The cleaning powders employed in such processes typically contain a liquid such as water, an organic solution or other such mixture. The liquid content of the powders adversely affects the spreadability of the powder since such powders tend to agglomerate or pack together. The coherency of the powder varies with the moisture content and with the porosity of the solid particulate matter employed. These powders typically have a liquid content of approximately 37%-41% by weight and must be spread fairly uniformly over the surface at a fairly constant rate to achieve acceptable cleaning results. Examples of such coherent cleaning powders may be found in U.S. Pat. No. 3,418,243 to Hoxie, entitled ART OF CLEANING CARPETS and issued on Dec. 24, 1968 and U.S. Pat. No. 4,019,662 to Dana, entitled FEEDER FOR COHERENT PARTICULATE MATERIAL and issued on Apr. 26, 1977.
The Dana patent also discloses a mechanical device primarily adapted to spread such coherent powders onto a carpeted surface. The device disclosed includes a storage bin having a lower, foraminous wall defining a plurality of perforations. A resilient reticulated foam cylinder is rotatably mounted within the bin. A foam cylinder is disposed to press against the wall and force powder from the bin through the perforations and hence onto the carpeted surface. In one embodiment of the device disclosed, the storage bin is mounted on a carpet cleaning machine which may include an agitator to work the powder into the surface. A separate independently driven motor is provided to rotate the foam cylinder when the bin is mounted on the carpet cleaning machine. A relatively powerful motor is required to rotate the foam cylinder and dispense the powder due to the frictional resistance of the cylinder to turning.
Other examples of devices developed to spread a powder like compound may be found in U.S. Pat. No. 2,650,002 to Farley, entitled APPARATUS FOR FEEDING FIBROUS MATERIAL and issued on Apr. 25, 1953; U.S. Pat. No. 2,797,847 to Barber et al, entitled SPREADER FOR FERTILIZER AND THE LIKE and issued on July 2, 1957; U.S. Pat. No. 3,620,423, entitled APPARATUS FOR DISTRIBUTING POWDER and issued on Nov. 16, 1971 to Dalgleish; U.S. Pat. No. 3,622,054 to Davidson, entitled TONER DISPENSER IMPROVEMENT and issued on Nov. 23, 1971; U.S. Pat. No. 3,774,814 to Vidjak, entitled METERING APPARATUS and issued on Nov. 27, 1973; U.S. Pat. No. 3,858,759 to Lubenow, entitled APPARATUS FOR VOLUMERIC FEEDING OF FIBROUS MATERIAL and issued on Jan. 7, 1975; and U.S. Pat. No. 3,946,910 to Case, entitled DRY TONER DISPENSER ASSEMBLY FOR COPYING MACHINE and issued on Mar. 30, 1976.
Although none of the later identified patents expressly relate to carpet cleaning apparatus, these patents do disclose various mechanical devices which have heretofore been proposed for the dispensing of wet powder compounds. For example, Case, U.S. Pat. No. 3,946,910 relates to a dispensing apparatus for depositing a dry toner for use in electrostatic copying machines and which employs an agitator disposed within a hopper to maintain the toner particles in a loose condition. Vidjak, U.S. Pat. No. 3,774,814 discloses a metering apparatus including a drum defining a plurality of longitudinally extending metering cavities and which further includes a cleaning idler. The apparatus is primarily adapted for metering moist cohesive material such as flaked fish material and rehydrated vegetables.
The devices heretofore available have not permitted selective use of a vacuum cleaner for conventional cleaning operations or for use with a cohesive powder dispenser. Also, such devices have typically required separately powdered motor drives for the powder dispensers and have not permitted selective use of the same vacuum cleaner for application of the powder and removal of the powder from the surface after it has been worked into the surface.